Ocean acidification causes variable trait-shifts in a coral species

Area of Science:

• Marine Biology
• Ecology
• Genetics

Background:

• High partial pressure of carbon dioxide (pCO2) habitats offer insights into species' survival under future ocean acidification.
• Astroides calycularis, a Mediterranean coral, is studied in a unique CO2 vent system to understand its response to elevated pCO2.

Purpose of the Study:

• To investigate trait-shifts in Astroides calycularis populations exposed to elevated pCO2.
• To identify traits conferring tolerance to ocean acidification.
• To explore genetic differentiation in response to environmental change.

Main Methods:

• Utilized a natural CO2 vent system to study Astroides calycularis.
• Analyzed skeletal and growth patterns.
• Conducted transcriptomic analysis to assess genetic differentiation.

Main Results:

• Colonies at low pH exhibited an encrusting morphology, smaller size, reduced tissue, fewer polyps, and denser skeletons.
• Individual polyps showed increased calcification and faster extension at low pH, but whole colonies maintained similar calcification and extension rates.
• Transcriptomic data revealed significant genetic differentiation in genes related to calcification, pH regulation, and carbon regulation in the CO2 vent population.

Conclusions:

• Coral populations can persist in high pCO2 environments through acclimatization and local adaptation.
• The studied CO2 vent system serves as a model for investigating organismal responses to global environmental change.
• Genetic differentiation in key regulatory genes suggests adaptive mechanisms for coping with ocean acidification.